Blocking routine redirection

ABSTRACT

Disclosed herein are methods, systems, and computer-readable media for blocking attempts at runtime redirection and attempts to change memory permissions during runtime. The present disclosure describes features that enable runtime detection of an attempt to redirect routines or change memory permissions, and determining whether to allow or deny the attempt. Such features may include changing memory write permissions on memory segments, such as those segments used by dynamic loaders after call associations have been saved or otherwise created. Other features may include swapping the addresses of system routines (e.g., open, read, write, close, etc.) to new routines that perform the same function as well as additional functionality configured to detect attempts to redirect or change memory permissions. Once detected by the new routine during runtime, a determination may be made to deny or allow the call based on a policy.

BACKGROUND

Aspects described herein generally relate to computer hardware andcomputer software, including software applications for mobile devicesand other computing devices. In particular, one or more aspects of thedisclosure are directed to computer software for blocking routineredirection or attempts to change memory permissions.

Mobile devices, such as smart phones, personal digital assistants,tablet computers, and other types of mobile computing devices are usefulin personal and business settings. In addition, users of mobile devicesmay install various mobile software applications suitable for a varietyof purposes. Mobile software applications may be developed by differententities and distributed from different sources, such as companiesdeveloping mobile business applications for their employees orindependent software vendors developing mobile consumer applications forpublic consumers. These software applications could be modified duringruntime by redirecting routine calls to different routines. Whenredirected, malicious code could be executed that alters or disruptsnormal runtime behavior.

SUMMARY

The following presents a simplified summary of various aspects describedherein. This summary is not an extensive overview, and is not intendedto identify key or critical elements or to delineate the scope of theclaims. The following summary merely presents some concepts in asimplified form as an introductory prelude to the more detaileddescription provided below. By performing various aspects of thisdisclosure, attempts to redirect routines or change memory permissions,attempts to execute malicious or otherwise unintended code that altersor disrupts normal runtime behavior may be blocked or prevented.

Some aspects of the disclosure relate to various systems, methods andfeatures that provide for the runtime detection of attempts to redirectroutines or change memory permissions. For example, various mechanismsfor detecting runtime attempts to redirect or change memory permissionsmay be established. Establishing such mechanisms may include, in someembodiments, determining a set of routines to replace, retrieving atable entry for one routine of the set of system routines from a symboltable; and determining an address of the one routine from the tableentry for the one routine. Additionally, establishing various mechanismsfor detecting runtime attempts to redirect or change memory permissionsmay include changing memory permissions to prevent writing to particularmemory segments, or establishing mechanisms, such as one or more otherdetection routines, for monitoring calls to one or more virtual filesystem operations. Detection routines may, in some embodiments, bedefined as a routine that includes code configured to detect an attemptto perform a runtime redirection and to detect an attempt to changememory permissions, and/or code configured to determine whether to allowor deny a detected attempt to perform a runtime redirection or changememory permissions

Other aspects of the disclosure relate to various systems, methods andfeatures that provide for a determination of whether to allow or deny anattempt to redirect routines or change memory permissions duringruntime. For example, determining whether to allow or deny an attempt toredirect routines or change memory permissions during runtime mayinclude executing, in response to a call to a system routine or avirtual file system operation, one of the detection routines. Executionof the detection routine may include determining whether the call is anattempt to redirect or change memory permissions; determining whether toallow or deny the call; and based on determining whether to allow ordeny the call; selecting between allowing the call in accordance with apolicy or denying the call in accordance with the policy.

These and additional aspects will be appreciated with the benefit of thedisclosures discussed in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of aspects described herein and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features, and wherein:

FIG. 1 depicts an illustrative computer system architecture that may beused in accordance with one or more illustrative aspects describedherein.

FIG. 2 depicts an illustrative remote-access system architecture thatmay be used in accordance with one or more illustrative aspectsdescribed herein.

FIG. 3 depicts an illustrative enterprise mobility management system.

FIG. 4 depicts another illustrative enterprise mobility managementsystem.

FIG. 5 illustrates an example algorithm of swizzling, call redirectionor routine hooking to inject malicious code during runtime.

FIG. 6 illustrates an example algorithm for establishing mechanisms fordetecting runtime redirection in accordance with one or moreillustrative aspects described herein.

FIG. 7 illustrates an example algorithm for determining whether to allowor deny a detected redirection or attempt to change memory permissionsin accordance with one or more illustrative aspects described herein.

DETAILED DESCRIPTION

In the following description of the various embodiments, reference ismade to the accompanying drawings identified above and which form a parthereof, and in which is shown by way of illustration various embodimentsin which aspects described herein may be practiced. It is to beunderstood that other embodiments may be utilized and structural andfunctional modifications may be made without departing from the scopedescribed herein. Various aspects are capable of other embodiments andof being practiced or being carried out in various different ways. It isto be understood that the phraseology and terminology used herein arefor the purpose of description and should not be regarded as limiting.Rather, the phrases and terms used herein are to be given their broadestinterpretation and meaning. The use of “including” and “comprising” andvariations thereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items and equivalents thereof.The use of the terms “mounted,” “connected,” “coupled,” “positioned,”“engaged” and similar terms, is meant to include both direct andindirect mounting, connecting, coupling, positioning and engaging.

As a general introduction to the subject matter described in more detailbelow, aspects described herein are directed towards features thatenable runtime detection of an attempt to redirect routines or changememory permissions during runtime, and determining whether to allow orblock the attempt. Such features may include changing memory writepermissions, such as on data segments used by dynamic loaders after thecall associations have been saved or created. Other features may includeswapping the addresses of system routines (e.g., open, read, write,close, etc.) to new routines that perform the same function as well asadditional functionality configured to detect attempts to redirect orchange memory permissions. Once detected by the new routine duringruntime, a determination may be made to block or allow the call based ona policy

Methods and systems supporting one or more of these features aredescribed in further detail below. Before discussing these concepts ingreater detail, however, several examples of computing devices andsystem architectures that may be used in implementing and/or otherwiseproviding various aspects of the disclosure will first be discussed withrespect to FIGS. 1-4.

Computing Architecture

Computer software, hardware, and networks may be utilized in a varietyof different system environments, including standalone, networked,remote-access (aka, remote desktop), virtualized, and/or cloud-basedenvironments, among others. FIG. 1 illustrates one example of a systemarchitecture and data processing device that may be used to implementone or more illustrative aspects described herein in a standalone and/ornetworked environment. Various network nodes 103, 105, 107, and 109 maybe interconnected via a wide area network (WAN) 101, such as theInternet. Other networks may also or alternatively be used, includingprivate intranets, corporate networks, LANs, metropolitan area networks(MAN) wireless networks, personal networks (PAN), and the like. Network101 is for illustration purposes and may be replaced with fewer oradditional computer networks. A local area network (LAN) may have one ormore of any known LAN topology and may use one or more of a variety ofdifferent protocols, such as Ethernet. Devices 103, 105, 107, 109 andother devices (not shown) may be connected to one or more of thenetworks via twisted pair wires, coaxial cable, fiber optics, radiowaves or other communication media.

The term “network” as used herein and depicted in the drawings refersnot only to systems in which remote storage devices are coupled togethervia one or more communication paths, but also to stand-alone devicesthat may be coupled, from time to time, to such systems that havestorage capability. Consequently, the term “network” includes not only a“physical network” but also a “content network,” which is comprised ofthe data—attributable to a single entity—which resides across allphysical networks.

The components may include data server 103, web server 105, and clientcomputers 107, 109. Data server 103 provides overall access, control andadministration of databases and control software for performing one ormore illustrative aspects describe herein. Data server 103 may beconnected to web server 105 through which users interact with and obtaindata as requested. Alternatively, data server 103 may act as a webserver itself and be directly connected to the Internet. Data server 103may be connected to web server 105 through the network 101 (e.g., theInternet), via direct or indirect connection, or via some other network.Users may interact with the data server 103 using remote computers 107,109, e.g., using a web browser to connect to the data server 103 via oneor more externally exposed web sites hosted by web server 105. Clientcomputers 107, 109 may be used in concert with data server 103 to accessdata stored therein, or may be used for other purposes. For example,from client device 107 a user may access web server 105 using anInternet browser, as is known in the art, or by executing a softwareapplication that communicates with web server 105 and/or data server 103over a computer network (such as the Internet).

Servers and applications may be combined on the same physical machines,and retain separate virtual or logical addresses, or may reside onseparate physical machines. FIG. 1 illustrates just one example of anetwork architecture that may be used, and those of skill in the artwill appreciate that the specific network architecture and dataprocessing devices used may vary, and are secondary to the functionalitythat they provide, as further described herein. For example, servicesprovided by web server 105 and data server 103 may be combined on asingle server.

Each component 103, 105, 107, 109 may be any type of known computer,server, or data processing device. Data server 103, e.g., may include aprocessor 111 controlling overall operation of the rate server 103. Dataserver 103 may further include random access memory (RAM) 113, read onlymemory (ROM) 115, network interface 117, input/output interfaces 119(e.g., keyboard, mouse, display, printer, etc.), and memory 121.Input/output (I/O) 119 may include a variety of interface units anddrives for reading, writing, displaying, and/or printing data or files.Memory 121 may further store operating system software 123 forcontrolling overall operation of the data processing device 103, controllogic 125 for instructing data server 103 to perform aspects describedherein, and other application software 127 providing secondary, support,and/or other functionality which may or might not be used in conjunctionwith aspects described herein. The control logic may also be referred toherein as the data server software 125. Functionality of the data serversoftware may refer to operations or decisions made automatically basedon rules coded into the control logic, made manually by a user providinginput into the system, and/or a combination of automatic processingbased on user input (e.g., queries, data updates, etc.).

Memory 121 may also store data used in performance of one or moreaspects described herein, including a first database 129 and a seconddatabase 131. In some embodiments, the first database may include thesecond database (e.g., as a separate table, report, etc.). That is, theinformation can be stored in a single database, or separated intodifferent logical, virtual, or physical databases, depending on systemdesign. Devices 105, 107, 109 may have similar or different architectureas described with respect to device 103. Those of skill in the art willappreciate that the functionality of data processing device 103 (ordevice 105, 107, 109) as described herein may be spread across multipledata processing devices, for example, to distribute processing loadacross multiple computers, to segregate transactions based on geographiclocation, user access level, quality of service (QoS), etc.

One or more aspects may be embodied in computer-usable or readable dataand/or computer-executable instructions, such as in one or more programmodules, executed by one or more computers or other devices as describedherein. Generally, program modules include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types when executed by a processor ina computer or other device. The modules may be written in a source codeprogramming language that is subsequently compiled for execution, or maybe written in a scripting language such as (but not limited to)HyperText Markup Language (HTML) or Extensible Markup Language (XML).The computer executable instructions may be stored on a computerreadable medium such as a nonvolatile storage device. Any suitablecomputer readable storage media may be utilized, including hard disks,CD-ROMs, optical storage devices, magnetic storage devices, and/or anycombination thereof. In addition, various transmission (non-storage)media representing data or events as described herein may be transferredbetween a source and a destination in the form of electromagnetic wavestraveling through signal-conducting media such as metal wires, opticalfibers, and/or wireless transmission media (e.g., air and/or space).Various aspects described herein may be embodied as a method, a dataprocessing system, or a computer program product. Therefore, variousfunctionalities may be embodied in whole or in part in software,firmware and/or hardware or hardware equivalents such as integratedcircuits, field programmable gate arrays (FPGA), and the like.Particular data structures may be used to more effectively implement oneor more aspects described herein, and such data structures arecontemplated within the scope of computer executable instructions andcomputer-usable data described herein.

With further reference to FIG. 2, one or more aspects described hereinmay be implemented in a remote-access environment. FIG. 2 depicts anexample system architecture including a generic computing device 201 inan illustrative computing environment 200 that may be used according toone or more illustrative aspects described herein. Generic computingdevice 201 may be used as a server 206 a in a single-server ormulti-server desktop virtualization system (e.g., a remote access orcloud system) configured to provide virtual machines for client accessdevices. The generic computing device 201 may have a processor 203 forcontrolling overall operation of the server and its associatedcomponents, including RAM 205, ROM 207, I/O module 209, and memory 215.

I/O module 209 may include a mouse, keypad, touch screen, scanner,optical reader, and/or stylus (or other input device(s)) through which auser of generic computing device 201 may provide input, and may alsoinclude one or more of a speaker for providing audio output and a videodisplay device for providing textual, audiovisual, and/or graphicaloutput. Software may be stored within memory 215 and/or other storage toprovide instructions to processor 203 for configuring generic computingdevice 201 into a special purpose computing device in order to performvarious functions as described herein. For example, memory 215 may storesoftware used by the computing device 201, such as an operating system217, application programs 219, and an associated database 221.

Computing device 201 may operate in a networked environment supportingconnections to one or more remote computers, such as terminals 240 (alsoreferred to as client devices). The terminals 240 may be personalcomputers, mobile devices, laptop computers, tablets, or servers thatinclude many or all of the elements described above with respect to thegeneric computing device 103 or 201. The network connections depicted inFIG. 2 include a local area network (LAN) 225 and a wide area network(WAN) 229, but may also include other networks. When used in a LANnetworking environment, computing device 201 may be connected to the LAN225 through a network interface or adapter 223. When used in a WANnetworking environment, computing device 201 may include a modem 227 orother wide area network interface for establishing communications overthe WAN 229, such as computer network 230 (e.g., the Internet). It willbe appreciated that the network connections shown are illustrative andother means of establishing a communications link between the computersmay be used. Computing device 201 and/or terminals 240 may also bemobile terminals (e.g., mobile phones, smartphones, personal digitalassistants (PDAs), notebooks, etc.) including various other components,such as a battery, speaker, and antennas (not shown).

Aspects described herein may also be operational with numerous othergeneral purpose or special purpose computing system environments orconfigurations. Examples of other computing systems, environments,and/or configurations that may be suitable for use with aspectsdescribed herein include, but are not limited to, personal computers,server computers, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network personal computers (PCs), minicomputers, mainframecomputers, distributed computing environments that include any of theabove systems or devices, and the like.

As shown in FIG. 2, one or more client devices 240 may be incommunication with one or more servers 206 a-206 n (generally referredto herein as “server(s) 206”). In one embodiment, the computingenvironment 200 may include a network appliance installed between theserver(s) 206 and client machine(s) 240. The network appliance maymanage client/server connections, and in some cases can load balanceclient connections amongst a plurality of backend servers 206.

The client machine(s) 240 may in some embodiments be referred to as asingle client machine 240 or a single group of client machines 240,while server(s) 206 may be referred to as a single server 206 or asingle group of servers 206. In one embodiment a single client machine240 communicates with more than one server 206, while in anotherembodiment a single server 206 communicates with more than one clientmachine 240. In yet another embodiment, a single client machine 240communicates with a single server 206.

A client machine 240 can, in some embodiments, be referenced by any oneof the following non-exhaustive terms: client machine(s); client(s);client computer(s); client device(s); client computing device(s); localmachine; remote machine; client node(s); endpoint(s); or endpointnode(s). The server 206, in some embodiments, may be referenced by anyone of the following non-exhaustive terms: server(s), local machine;remote machine; server farm(s), or host computing device(s).

In one embodiment, the client machine 240 may be a virtual machine. Thevirtual machine may be any virtual machine, while in some embodimentsthe virtual machine may be any virtual machine managed by a Type 1 orType 2 hypervisor, for example, a hypervisor developed by CitrixSystems, IBM, VMware, or any other hypervisor. In some aspects, thevirtual machine may be managed by a hypervisor, while in aspects thevirtual machine may be managed by a hypervisor executing on a server 206or a hypervisor executing on a client 240.

Some embodiments include a client device 240 that displays applicationoutput generated by an application remotely executing on a server 206 orother remotely located machine. In these embodiments, the client device240 may execute a virtual machine receiver program or application todisplay the output in an application window, a browser, or other outputwindow. In one example, the application is a desktop, while in otherexamples the application is an application that generates or presents adesktop. A desktop may include a graphical shell providing a userinterface for an instance of an operating system in which local and/orremote applications can be integrated. Applications, as used herein, areprograms that execute after an instance of an operating system (and,optionally, also the desktop) has been loaded.

The server 206, in some embodiments, uses a remote presentation protocolor other program to send data to a thin-client or remote-displayapplication executing on the client to present display output generatedby an application executing on the server 206. The thin-client orremote-display protocol can be any one of the following non-exhaustivelist of protocols: the Independent Computing Architecture (ICA) protocoldeveloped by Citrix Systems, Inc. of Ft. Lauderdale, Fla.; or the RemoteDesktop Protocol (RDP) manufactured by the Microsoft Corporation ofRedmond, Wash.

A remote computing environment may include more than one server 206a-206 n such that the servers 206 a-206 n are logically grouped togetherinto a server farm 206, for example, in a cloud computing environment.The server farm 206 may include servers 206 that are geographicallydispersed while and logically grouped together, or servers 206 that arelocated proximate to each other while logically grouped together.Geographically dispersed servers 206 a-206 n within a server farm 206can, in some embodiments, communicate using a WAN (wide), MAN(metropolitan), or LAN (local), where different geographic regions canbe characterized as: different continents; different regions of acontinent; different countries; different states; different cities;different campuses; different rooms; or any combination of the precedinggeographical locations. In some embodiments the server farm 206 may beadministered as a single entity, while in other embodiments the serverfarm 206 can include multiple server farms.

In some embodiments, a server farm may include servers 206 that executea substantially similar type of operating system platform (e.g.,WINDOWS, UNIX, LINUX, iOS, ANDROID, SYMBIAN, etc.) In other embodiments,server farm 206 may include a first group of one or more servers thatexecute a first type of operating system platform, and a second group ofone or more servers that execute a second type of operating systemplatform.

Server 206 may be configured as any type of server, as needed, e.g., afile server, an application server, a web server, a proxy server, anappliance, a network appliance, a gateway, an application gateway, agateway server, a virtualization server, a deployment server, a SecureSockets Layer (SSL) VPN server, a firewall, a web server, an applicationserver or as a master application server, a server executing an activedirectory, or a server executing an application acceleration programthat provides firewall functionality, application functionality, or loadbalancing functionality. Other server types may also be used.

Some embodiments include a first server 106 a that receives requestsfrom a client machine 240, forwards the request to a second server 106b, and responds to the request generated by the client machine 240 witha response from the second server 106 b. First server 106 a may acquirean enumeration of applications available to the client machine 240 andwell as address information associated with an application server 206hosting an application identified within the enumeration ofapplications. First server 106 a can then present a response to theclient's request using a web interface, and communicate directly withthe client 240 to provide the client 240 with access to an identifiedapplication. One or more clients 240 and/or one or more servers 206 maytransmit data over network 230, e.g., network 101.

FIG. 2 shows a high-level architecture of an illustrative desktopvirtualization system. As shown, the desktop virtualization system maybe single-server or multi-server system, or cloud system, including atleast one virtualization server 206 configured to provide virtualdesktops and/or virtual applications to one or more client accessdevices 240. As used herein, a desktop refers to a graphical environmentor space in which one or more applications may be hosted and/orexecuted. A desktop may include a graphical shell providing a userinterface for an instance of an operating system in which local and/orremote applications can be integrated. Applications may include programsthat execute after an instance of an operating system (and, optionally,also the desktop) has been loaded. Each instance of the operating systemmay be physical (e.g., one operating system per device) or virtual(e.g., many instances of an OS running on a single device). Eachapplication may be executed on a local device, or executed on a remotelylocated device (e.g., remoted).

Enterprise Mobility Management Architecture

FIG. 3 represents an enterprise mobility technical architecture 300 foruse in a BYOD environment. The architecture enables a user of a clientdevice (e.g., mobile device) 302 to both access enterprise or personalresources from a mobile device 302 and use the mobile device 302 forpersonal use. The user may access such enterprise resources 304 orenterprise services 308 using a mobile device 302 that is purchased bythe user or a mobile device 302 that is provided by the enterprise touser. The user may utilize the mobile device 302 for business use onlyor for business and personal use. The mobile device may run an iOSoperating system, and Android operating system, or the like. Theenterprise may choose to implement policies to manage the mobile device302. The policies may be implanted through a firewall or gateway in sucha way that the mobile device may be identified, secured or securityverified, and provided selective or full access to the enterpriseresources. The policies may be mobile device management policies, mobileapplication management policies, mobile data management policies, orsome combination of mobile device, application, and data managementpolicies. A mobile device 302 that is managed through the application ofmobile device management policies may be referred to as an enrolleddevice.

In some embodiments, the operating system of the mobile device may beseparated into a managed partition 310 and an unmanaged partition 312.The managed partition 310 may have policies applied to it to secure theapplications running on and data stored in the managed partition. Theapplications running on the managed partition may be secureapplications. In other embodiments, all applications may execute inaccordance with a set of one or more policy files received separate fromthe application, and which define one or more security parameters,features, resource restrictions, and/or other access controls that areenforced by the mobile device management system when that application isexecuting on the device. By operating in accordance with theirrespective policy file(s), each application may be allowed or restrictedfrom communications with one or more other applications and/orresources, thereby creating a virtual partition. Thus, as used herein, apartition may refer to a physically partitioned portion of memory(physical partition), a logically partitioned portion of memory (logicalpartition), and/or a virtual partition created as a result ofenforcement of one or more policies and/or policy files across multipleapps as described herein (virtual partition). Stated differently, byenforcing policies on managed apps, those apps may be restricted to onlybe able to communicate with other managed apps and trusted enterpriseresources, thereby creating a virtual partition that is impenetrable byunmanaged apps and devices.

The secure applications may be email applications, web browsingapplications, software-as-a-service (SaaS) access applications, WindowsApplication access applications, and the like. The secure applicationsmay be secure native applications 314, secure remote applications 322executed by a secure application launcher 318, virtualizationapplications 326 executed by a secure application launcher 318, and thelike. The secure native applications 314 may be wrapped by a secureapplication wrapper 320. The secure application wrapper 320 may includeintegrated policies that are executed on the mobile device 302 when thesecure native application is executed on the device. The secureapplication wrapper 320 may include meta-data that points the securenative application 314 running on the mobile device 302 to the resourceshosted at the enterprise that the secure native application 314 mayrequire to complete the task requested upon execution of the securenative application 314. The secure remote applications 322 executed by asecure application launcher 318 may be executed within the secureapplication launcher application 318. The virtualization applications326 executed by a secure application launcher 318 may utilize resourceson the mobile device 302, at the enterprise resources 304, and the like.The resources used on the mobile device 302 by the virtualizationapplications 326 executed by a secure application launcher 318 mayinclude user interaction resources, processing resources, and the like.The user interaction resources may be used to collect and transmitkeyboard input, mouse input, camera input, tactile input, audio input,visual input, gesture input, and the like. The processing resources maybe used to present a user interface, process data received from theenterprise resources 304, and the like. The resources used at theenterprise resources 304 by the virtualization applications 326 executedby a secure application launcher 318 may include user interfacegeneration resources, processing resources, and the like. The userinterface generation resources may be used to assemble a user interface,modify a user interface, refresh a user interface, and the like. Theprocessing resources may be used to create information, readinformation, update information, delete information, and the like. Forexample, the virtualization application may record user interactionsassociated with a graphical user interface (GUI) and communicate them toa server application where the server application will use the userinteraction data as an input to the application operating on the server.In this arrangement, an enterprise may elect to maintain the applicationon the server side as well as data, files, etc. associated with theapplication. While an enterprise may elect to “mobilize” someapplications in accordance with the principles herein by securing themfor deployment on the mobile device, this arrangement may also beelected for certain applications. For example, while some applicationsmay be secured for use on the mobile device, others might not beprepared or appropriate for deployment on the mobile device so theenterprise may elect to provide the mobile user access to the unpreparedapplications through virtualization techniques. As another example, theenterprise may have large complex applications with large and complexdata sets (e.g., material resource planning applications) where it wouldbe very difficult, or otherwise undesirable, to customize theapplication for the mobile device so the enterprise may elect to provideaccess to the application through virtualization techniques. As yetanother example, the enterprise may have an application that maintainshighly secured data (e.g., human resources data, customer data,engineering data) that may be deemed by the enterprise as too sensitivefor even the secured mobile environment so the enterprise may elect touse virtualization techniques to permit mobile access to suchapplications and data. An enterprise may elect to provide both fullysecured and fully functional applications on the mobile device as wellas a virtualization application to allow access to applications that aredeemed more properly operated on the server side. In an embodiment, thevirtualization application may store some data, files, etc. on themobile phone in one of the secure storage locations. An enterprise, forexample, may elect to allow certain information to be stored on thephone while not permitting other information.

In connection with the virtualization application, as described herein,the mobile device may have a virtualization application that is designedto present GUIs and then record user interactions with the GUI. Theapplication may communicate the user interactions to the server side tobe used by the server side application as user interactions with theapplication. In response, the application on the server side maytransmit back to the mobile device a new GUI. For example, the new GUImay be a static page, a dynamic page, an animation, or the like, therebyproviding access to remotely located resources.

The secure applications may access data stored in a secure datacontainer 328 in the managed partition 310 of the mobile device. Thedata secured in the secure data container may be accessed by the securewrapped applications 314, applications executed by a secure applicationlauncher 322, virtualization applications 326 executed by a secureapplication launcher 322, and the like. The data stored in the securedata container 328 may include files, databases, and the like. The datastored in the secure data container 328 may include data restricted to aspecific secure application 330, shared among secure applications 332,and the like. Data restricted to a secure application may include securegeneral data 334 and highly secure data 338. Secure general data may usea strong form of encryption such as Advanced Encryption Standard (AES)128-bit encryption or the like, while highly secure data 338 may use avery strong form of encryption such as AES 256-bit encryption. Datastored in the secure data container 328 may be deleted from the deviceupon receipt of a command from the device manager 324. The secureapplications may have a dual-mode option 340. The dual mode option 340may present the user with an option to operate the secured applicationin an unsecured or unmanaged mode. In an unsecured or unmanaged mode,the secure applications may access data stored in an unsecured datacontainer 342 on the unmanaged partition 312 of the mobile device 302.The data stored in an unsecured data container may be personal data 344.The data stored in an unsecured data container 342 may also be accessedby unsecured applications 548 that are running on the unmanagedpartition 312 of the mobile device 302. The data stored in an unsecureddata container 342 may remain on the mobile device 302 when the datastored in the secure data container 328 is deleted from the mobiledevice 302. An enterprise may want to delete from the mobile deviceselected or all data, files, and/or applications owned, licensed orcontrolled by the enterprise (enterprise data) while leaving orotherwise preserving personal data, files, and/or applications owned,licensed or controlled by the user (personal data). This operation maybe referred to as a selective wipe. With the enterprise and personaldata arranged in accordance to the aspects described herein, anenterprise may perform a selective wipe.

The mobile device may connect to enterprise resources 304 and enterpriseservices 308 at an enterprise, to the public Internet 348, and the like.The mobile device may connect to enterprise resources 304 and enterpriseservices 308 through virtual private network connections. The virtualprivate network connections, also referred to as microVPN orapplication-specific VPN, may be specific to particular applications350, particular devices, particular secured areas on the mobile device,and the like 352. For example, each of the wrapped applications in thesecured area of the phone may access enterprise resources through anapplication specific VPN such that access to the VPN would be grantedbased on attributes associated with the application, possibly inconjunction with user or device attribute information. The virtualprivate network connections may carry Microsoft Exchange traffic,Microsoft Active Directory traffic, HyperText Transfer Protocol (HTTP)traffic, HyperText Transfer Protocol Secure (HTTPS) traffic, applicationmanagement traffic, and the like. The virtual private networkconnections may support and enable single-sign-on authenticationprocesses 354. The single-sign-on processes may allow a user to providea single set of authentication credentials, which are then verified byan authentication service 358. The authentication service 358 may thengrant to the user access to multiple enterprise resources 304, withoutrequiring the user to provide authentication credentials to eachindividual enterprise resource 304.

The virtual private network connections may be established and managedby an access gateway 360. The access gateway 360 may include performanceenhancement features that manage, accelerate, and improve the deliveryof enterprise resources 304 to the mobile device 302. The access gatewaymay also re-route traffic from the mobile device 302 to the publicInternet 348, enabling the mobile device 302 to access publiclyavailable and unsecured applications that run on the public Internet348. The mobile device may connect to the access gateway via a transportnetwork 362. The transport network 362 may be a wired network, wirelessnetwork, cloud network, local area network, metropolitan area network,wide area network, public network, private network, and the like.

The enterprise resources 304 may include email servers, file sharingservers, SaaS applications, Web application servers, Windows applicationservers, and the like. Email servers may include Exchange servers, LotusNotes servers, and the like. File sharing servers may include ShareFileservers, and the like. SaaS applications may include Salesforce, and thelike. Windows application servers may include any application serverthat is built to provide applications that are intended to run on alocal Windows operating system, and the like. The enterprise resources304 may be premise-based resources, cloud based resources, and the like.The enterprise resources 304 may be accessed by the mobile device 302directly or through the access gateway 360. The enterprise resources 304may be accessed by the mobile device 302 via a transport network 362.The transport network 362 may be a wired network, wireless network,cloud network, local area network, metropolitan area network, wide areanetwork, public network, private network, and the like.

The enterprise services 308 may include authentication services 358,threat detection services 364, device manager services 324, file sharingservices 368, policy manager services 370, social integration services372, application controller services 374, and the like. Authenticationservices 358 may include user authentication services, deviceauthentication services, application authentication services, dataauthentication services and the like. Authentication services 358 mayuse certificates. The certificates may be stored on the mobile device302, by the enterprise resources 304, and the like. The certificatesstored on the mobile device 302 may be stored in an encrypted locationon the mobile device, the certificate may be temporarily stored on themobile device 302 for use at the time of authentication, and the like.Threat detection services 364 may include intrusion detection services,unauthorized access attempt detection services, and the like.Unauthorized access attempt detection services may include unauthorizedattempts to access devices, applications, data, and the like. Devicemanagement services 324 may include configuration, provisioning,security, support, monitoring, reporting, and decommissioning services.File sharing services 368 may include file management services, filestorage services, file collaboration services, and the like. Policymanager services 370 may include device policy manager services,application policy manager services, data policy manager services, andthe like. Social integration services 372 may include contactintegration services, collaboration services, integration with socialnetworks such as Facebook, Twitter, and LinkedIn, and the like.Application controller services 374 may include management services,provisioning services, deployment services, assignment services,revocation services, wrapping services, and the like.

The enterprise mobility technical architecture 300 may include anapplication store 378. The application store 378 may include unwrappedapplications 380, pre-wrapped applications 382, and the like.Applications may be populated in the application store 378 from theapplication controller 374. The application store 378 may be accessed bythe mobile device 302 through the access gateway 360, through the publicInternet 348, or the like. The application store may be provided with anintuitive and easy to use User Interface.

A software development kit 384 may provide a user the capability tosecure applications selected by the user by wrapping the application asdescribed previously in this description. An application that has beenwrapped using the software development kit 384 may then be madeavailable to the mobile device 302 by populating it in the applicationstore 378 using the application controller 374.

The enterprise mobility technical architecture 300 may include amanagement and analytics capability 388. The management and analyticscapability 388 may provide information related to how resources areused, how often resources are used, and the like. Resources may includedevices, applications, data, and the like. How resources are used mayinclude which devices download which applications, which applicationsaccess which data, and the like. How often resources are used mayinclude how often an application has been downloaded, how many times aspecific set of data has been accessed by an application, and the like.

FIG. 4 is another illustrative enterprise mobility management system400. Some of the components of the mobility management system 300described above with reference to FIG. 3 have been omitted for the sakeof simplicity. The architecture of the system 400 depicted in FIG. 4 issimilar in many respects to the architecture of the system 400 describedabove with reference to FIG. 3 and may include additional features notmentioned above.

In this case, the left hand side represents an enrolled client device(e.g., mobile device) 402 with a client agent 404, which interacts withgateway server 406 (which includes Access Gateway and applicationcontroller functionality) to access various enterprise resources 408 andservices 409 such as Exchange, Sharepoint, public-key infrastructure(PKI) Resources, Kerberos Resources, Certificate Issuance service, asshown on the right hand side above. Although not specifically shown, themobile device 402 may also interact with an enterprise application store(StoreFront) for the selection and downloading of applications.

The client agent 404 acts as the UI (user interface) intermediary forWindows apps/desktops hosted in an Enterprise data center, which areaccessed using the High-Definition User Experience (HDX)/ICA displayremoting protocol. The client agent 404 also supports the installationand management of native applications on the mobile device 402, such asnative iOS or Android applications. For example, the managedapplications 410 (mail, browser, wrapped application) shown in thefigure above are all native applications that execute locally on thedevice. Client agent 404 and application management framework of thisarchitecture act to provide policy driven management capabilities andfeatures such as connectivity and SSO (single sign on) to enterpriseresources/services 408. The client agent 404 handles primary userauthentication to the enterprise, normally to Access Gateway (AG) withSSO to other gateway server components. The client agent 404 obtainspolicies from gateway server 406 to control the behavior of the managedapplications 410 on the mobile device 402.

The Secure interprocess communication (IPC) links 412 between the nativeapplications 410 and client agent 404 represent a management channel,which allows client agent to supply policies to be enforced by theapplication management framework 414 “wrapping” each application. TheIPC channel 412 also allows client agent 404 to supply credential andauthentication information that enables connectivity and SSO toenterprise resources 408. Finally the IPC channel 412 allows theapplication management framework 414 to invoke user interface functionsimplemented by client agent 404, such as online and offlineauthentication.

Communications between the client agent 404 and gateway server 406 areessentially an extension of the management channel from the applicationmanagement framework 414 wrapping each native managed application 410.The application management framework 414 requests policy informationfrom client agent 404, which in turn requests it from gateway server406. The application management framework 414 requests authentication,and client agent 404 logs into the gateway services part of gatewayserver 406 (also known as NetScaler Access Gateway). Client agent 404may also call supporting services on gateway server 406, which mayproduce input material to derive encryption keys for the local datavaults 416, or provide client certificates which may enable directauthentication to PKI protected resources, as more fully explainedbelow.

In more detail, the application management framework 414 “wraps” eachmanaged application 410. This may be incorporated via an explicit buildstep, or via a post-build processing step. The application managementframework 414 may “pair” with client agent 404 on first launch of anapplication 410 to initialize the Secure IPC channel and obtain thepolicy for that application. The application management framework 414may enforce relevant portions of the policy that apply locally, such asthe client agent login dependencies and some of the containment policiesthat restrict how local OS services may be used, or how they mayinteract with the application 410.

The application management framework 414 may use services provided byclient agent 404 over the Secure IPC channel 412 to facilitateauthentication and internal network access. Key management for theprivate and shared data vaults 416 (containers) may be also managed byappropriate interactions between the managed applications 410 and clientagent 404. Vaults 416 may be available only after online authentication,or may be made available after offline authentication if allowed bypolicy. First use of vaults 416 may require online authentication, andoffline access may be limited to at most the policy refresh periodbefore online authentication is again required.

Network access to internal resources may occur directly from individualmanaged applications 410 through Access Gateway 406. The applicationmanagement framework 414 is responsible for orchestrating the networkaccess on behalf of each application 410. Client agent 404 mayfacilitate these network connections by providing suitable time limitedsecondary credentials obtained following online authentication. Multiplemodes of network connection may be used, such as reverse web proxyconnections and end-to-end VPN-style tunnels 418.

The Mail and Browser managed applications 410 have special status andmay make use of facilities that might not be generally available toarbitrary wrapped applications. For example, the Mail application mayuse a special background network access mechanism that allows it toaccess Exchange over an extended period of time without requiring a fullAG logon. The Browser application may use multiple private data vaultsto segregate different kinds of data.

This architecture supports the incorporation of various other securityfeatures. For example, gateway server 406 (including its gatewayservices) in some cases will not need to validate active directory (AD)passwords. It can be left to the discretion of an enterprise whether anAD password is used as an authentication factor for some users in somesituations. Different authentication methods may be used if a user isonline or offline (i.e., connected or not connected to a network).

Step up authentication is a feature in which gateway server 406 mayidentify managed native applications 410 that are allowed to have accessto highly classified data requiring strong authentication, and ensurethat access to these applications is only permitted after performingappropriate authentication, even if this means a re-authentication isrequired by the user after a prior weaker level of login.

Another security feature of this solution is the encryption of the datavaults 416 (containers) on the mobile device 402. The vaults 416 may beencrypted so that all on-device data including files, databases, andconfigurations are protected. For on-line vaults, the keys may be storedon the server (gateway server 406), and for off-line vaults, a localcopy of the keys may be protected by a user password or biometricvalidation. When data is stored locally on the device 402 in the securecontainer 416, it is preferred that a minimum of AES 256 encryptionalgorithm be utilized.

Other secure container features may also be implemented. For example, alogging feature may be included, in which all security events happeninginside an application 410 are logged and reported to the backend. Datawiping may be supported, such as if the application 410 detectstampering, associated encryption keys may be written over with randomdata, leaving no hint on the file system that user data was destroyed.Screenshot protection is another feature, where an application mayprevent any data from being stored in screenshots. For example, the keywindow's hidden property may be set to YES. This may cause whatevercontent is currently displayed on the screen to be hidden, resulting ina blank screenshot where any content would normally reside.

Local data transfer may be prevented, such as by preventing any datafrom being locally transferred outside the application container, e.g.,by copying it or sending it to an external application. A keyboard cachefeature may operate to disable the autocorrect functionality forsensitive text fields. SSL certificate validation may be operable so theapplication specifically validates the server SSL certificate instead ofit being stored in the keychain. An encryption key generation featuremay be used such that the key used to encrypt data on the device isgenerated using a passphrase or biometric data supplied by the user (ifoffline access is required). It may be XORed with another key randomlygenerated and stored on the server side if offline access is notrequired. Key Derivation functions may operate such that keys generatedfrom the user password use KDFs (key derivation functions, notablyPassword-Based Key Derivation Function 2 (PBKDF2)) rather than creatinga cryptographic hash of it. The latter makes a key susceptible to bruteforce or dictionary attacks.

Further, one or more initialization vectors may be used in encryptionmethods. An initialization vector will cause multiple copies of the sameencrypted data to yield different cipher text output, preventing bothreplay and cryptanalytic attacks. This will also prevent an attackerfrom decrypting any data even with a stolen encryption key if thespecific initialization vector used to encrypt the data is not known.Further, authentication then decryption may be used, in whichapplication data is decrypted only after the user has authenticatedwithin the application. Another feature may relate to sensitive data inmemory, which may be kept in memory (and not in disk) only when it'sneeded. For example, login credentials may be wiped from memory afterlogin, and encryption keys and other data inside objective-C instancevariables are not stored, as they may be easily referenced. Instead,memory may be manually allocated for these.

An inactivity timeout may be implemented, in which after apolicy-defined period of inactivity, a user session is terminated.

Data leakage from the application management framework 414 may beprevented in other ways. For example, when an application 410 is put inthe background, the memory may be cleared after a predetermined(configurable) time period. When backgrounded, a snapshot may be takenof the last displayed screen of the application to fasten theforegrounding process. The screenshot may contain confidential data andhence should be cleared.

Another security feature relates to the use of an OTP (one timepassword) 420 without the use of an AD (active directory) 422 passwordfor access to one or more applications. In some cases, some users do notknow (or are not permitted to know) their AD password, so these usersmay authenticate using an OTP 420 such as by using a hardware OTP systemlike SecurID (OTPs may be provided by different vendors also, such asEntrust or Gemalto). In some cases, after a user authenticates with auser ID, a text is sent to the user with an OTP 420. In some cases, thismay be implemented only for online use, with a prompt being a singlefield.

An offline password may be implemented for offline authentication forthose applications 410 for which offline use is permitted via enterprisepolicy. For example, an enterprise may want StoreFront to be accessed inthis manner. In this case, the client agent 404 may require the user toset a custom offline password and the AD password is not used. Gatewayserver 406 may provide policies to control and enforce passwordstandards with respect to the minimum length, character classcomposition, and age of passwords, such as described by the standardWindows Server password complexity requirements, although theserequirements may be modified.

Another feature relates to the enablement of a client side certificatefor certain applications 410 as secondary credentials (for the purposeof accessing PKI protected web resources via the application managementframework micro VPN feature). For example, an application may utilizesuch a certificate. In this case, certificate-based authentication usingActiveSync protocol may be supported, in which a certificate from theclient agent 404 may be retrieved by gateway server 406 and used in akeychain. Each managed application may have one associated clientcertificate, identified by a label that is defined in gateway server406.

Gateway server 406 may interact with an Enterprise special purpose webservice to support the issuance of client certificates to allow relevantmanaged applications to authenticate to internal PKI protectedresources.

The client agent 404 and the application management framework 414 may beenhanced to support obtaining and using client certificates forauthentication to internal PKI protected network resources. More thanone certificate may be supported, such as to match various levels ofsecurity and/or separation requirements. The certificates may be used bythe Mail and Browser managed applications, and ultimately by arbitrarywrapped applications (provided those applications use web service stylecommunication patterns where it is reasonable for the applicationmanagement framework to mediate https requests).

Application management client certificate support on iOS may rely onimporting a public-key cryptography standards (PKCS) 12 BLOB (BinaryLarge Object) into the iOS keychain in each managed application for eachperiod of use. Application management framework client certificatesupport may use a HTTPS implementation with private in-memory keystorage. The client certificate will never be present in the iOSkeychain and will not be persisted except potentially in “online-only”data value that is strongly protected.

Mutual SSL may also be implemented to provide additional security byrequiring that a mobile device 402 is authenticated to the enterprise,and vice versa. Virtual smart cards for authentication to gateway server406 may also be implemented.

Both limited and full Kerberos support may be additional features. Thefull support feature relates to an ability to do full Kerberos login toActive Directory (AD) 422, using an AD password or trusted clientcertificate, and obtain Kerberos service tickets to respond to HTTPNegotiate authentication challenges. The limited support feature relatesto constrained delegation in Citrix Access Gateway Enterprise Edition(AGEE), where AGEE supports invoking Kerberos protocol transition so itcan obtain and use Kerberos service tickets (subject to constraineddelegation) in response to HTTP Negotiate authentication challenges.This mechanism works in reverse web proxy (aka corporate virtual privatenetwork (CVPN)) mode, and when http (but not https) connections areproxied in VPN and MicroVPN mode.

Another feature relates to application container locking and wiping,which may automatically occur upon jail-break or rooting detections, andoccur as a pushed command from administration console, and may include aremote wipe functionality even when an application 410 is not running.

A multi-site architecture or configuration of enterprise applicationstore and an application controller may be supported that allows usersto be serviced from one of several different locations in case offailure.

In some cases, managed applications 410 may be allowed to access acertificate and private key via an API (example OpenSSL). Trustedmanaged applications 410 of an enterprise may be allowed to performspecific Public Key operations with an application's client certificateand private key. Various use cases may be identified and treatedaccordingly, such as when an application behaves like a browser and nocertificate access is required, when an application reads a certificatefor “who am I,” when an application uses the certificate to build asecure session token, and when an application uses private keys fordigital signing of important data (e.g. transaction log) or fortemporary data encryption.

Illustrative Embodiments

Having discussed several examples of computing architectures and theenterprise mobility management architecture that may be used inproviding and/or implementing various aspects of the disclosure, anumber of embodiments will now be discussed in greater detail. Inparticular, and as introduced above, some aspects of the disclosuregenerally relate to blocking routine redirection and changing memorypermissions. The present disclosure describes features that enableruntime detection of an attempt to redirect routines or change memorypermissions during runtime, and determining whether to allow or blockthe attempt. Such features may include changing memory writepermissions, such as on data segments used by dynamic loaders after thecall associations have been saved or created. Other features may includeswapping the addresses of system routines (e.g., open, read, write,close, etc.) to new routines that perform the same function as well asadditional functionality configured to detect attempts to redirect orchange memory permissions. Once detected by the new routine duringruntime, a determination may be made to block or allow the call based ona policy.

FIGS. 5-7 illustrate various examples of algorithms and methods inaccordance with one or more features described herein. The features,algorithms and methods described below in reference to FIGS. 5-7 may beperformed by a computing device or a combination of devices, such as thevarious computing devices and systems shown in FIGS. 1-4. The features,steps, algorithms and methods described below in reference to FIGS. 5-7may, in some instances, be performed in any order, and one or morefeatures, steps, algorithms or methods may be omitted and/or added. Oneor more aspects illustrated in FIGS. 5-7 relate to blocking routineredirection and/or preventing an attempt to change memory permissions.For example, applications on the mobile device 302 or 402, such asapplications from the application store 378, managed applications 410,or applications in unmanaged partition 312 may be injected withmalicious code by redirecting system calls or calls to other routines todifferent routines that include the malicious code. By performing theexample algorithms or methods of FIGS. 5-7, attempts to executemalicious code may be prevented or otherwise blocked.

In particular, one manner in which malicious code may be injected is byswizzling, call redirection or routing hooking. Swizzling, callredirection or routine hooking may change the functionality of a methodor routine by replacing one implementation with another. In variousinstances, swizzling, call redirection and routing hooking can beperformed at runtime. FIG. 5 illustrates an example method of swizzling,call redirection or routing hooking to inject malicious code duringruntime. In particular, FIG. 5 illustrates an example algorithm ofswizzling, call redirection or routine hooking, e.g., using Objective-C,which allows for the swizzling of routines via the Objective-C Runtime.Objective-C Runtime is a library that includes various methods forclasses and objects in Objective-C. Additionally, the Objective-CRuntime is primarily coded in C and assembly language and, broadly,provides the object-oriented features of Objective-C. There are a numberof ways in which Objective-C can be swizzled. The steps of FIG. 5 willbe described in connection with two different types of swizzling, callredirection or routine hooking: one that exchanges implementations ofObjective-C methods to replace an original implementation, and anotherthat sets the implementation to a C method to replace the originalimplementation. For brevity, when referring to swizzling, callredirection or routine hooking, the below examples will refer only to aroutine being swizzled or a routine being redirected.

At step 501, a routine that will be exchanged for the originalimplementation is created. As one example, an Objective-C routine may becreated. The Objective-C routine may include additional code and, often,may call the original implementation. For example, if one wants to addto the functionality of a routine that opens a file, a new routine maybe written that includes code for performing the desired additionalfunctionality and also calls the routine that opens a file. Duringcompilation, Objective-C can generate structures that define a routineand by manipulating these structures (as described in connection withsteps 503 and 505 of FIG. 5) the original implementation may be swizzledor redirected. In Objective-C, the structure that defines a routineincludes a selector name for the routine, a string of the parameters andreturn value for the routine, and a pointer to the memory location ofthe routine.

As a second example, a C routine may be created. The C routine mayconform to the signature of the routine that is to be swizzled orredirected. The signature of the routine includes any parameters thatare passed when calling the routine, as well as the hidden parametersthat every Objective-C method uses (e.g., a reference to self and aselector of the routine). As will be described in connection with steps503 and 505, this C routine may be set as the implementation tosuccessfully swizzle or redirect the original implementation. Similar tothe Objective-C routine, the C routine may include code for performingdesired additional functionality and, often, may call the originalimplementation.

The additional code of the Objective-C routine and the C routine may, insome instances, include malicious code that alters the functionality ofsoftware in ways that are undesirable to the software's creator, user ofa device, or an employer of the user. One of the features of the presentdisclosure is to block runtime redirections, such as swizzling, toprevent the execution of such malicious code.

At step 503, pointers to the created routine and/or the originalimplementation may be determined. For the example using the Objective-Croutine, the pointer to the original implementation can be determinedusing the ‘class_getInstanceMethod’ of the Objective-C Runtime with oneof the parameters being the pointer to the selector of the originalimplementation. The pointer to the created routine may be determinedusing the ‘class_getInstanceMethod’ with one of the parameters being thepointer to the selector of the created routine.

For the example using the C routine, the pointer to the created routinecan be determined by casting the function as an implementation type ofObjective-C (e.g., IMP). The pointer to the original implementation willbe determined at step 505.

At step 505, the implementations of the original implementation and thecreated routine may be exchanged in order to execute the created routineinstead of the original implementation. For the example using theObjective-C routine, the implementations may be exchanged using‘method_exchangeImplementations’ of the Objective-C Runtime with theparameters being the pointers to the original implementation and thecreated routine. The exchange causes the structures of the originalimplementation and the created routine to swap variables. For example,the structure of the original implementation will now include a pointerto the memory location of the created routine. The structure of thecreated routine will now include a pointer to the memory location of theoriginal implementation.

For the example using the C routine, the implementation of the createdroutine may be set using the ‘method_setImplementation’ of theObjective-C Runtime with one of the parameters being the IMP of thecreated routine. This call returns an IMP of the original implementationof the routine, which can be used to call the original implementation ofthe routine.

At step 507, the created routine may, during runtime, be executed upon acall instead of the original implementation. After completing theswizzling or redirecting described in the above steps, the createdroutine may be executed in response to a call to the originalimplementation. Accordingly, the additional code of the created routinewill be executed. The original implementation will often also beexecuted since the created routine often calls the originalimplementation (e.g., via a self-call, which causes the originalimplementation to be executed due to the call to‘method_exchangeImplementation’; or via a call to the IMP returned from‘method_setImplementation’).

In an attempt to prevent the execution of malicious code caused byruntime redirection, mechanisms for detecting runtime redirection (e.g.,swizzling, redirecting, hooking) may be established and, during runtime,a determination may be performed as to whether to allow or deny adetected redirection or attempt to change memory permissions. FIGS. 6and 7 illustrate example algorithms and methods for establishing themechanisms for detecting runtime redirection (also referred herein asdetection mechanisms) and determining whether to allow or deny adetected redirection or attempt to change memory permissions.

FIG. 6 illustrates an example algorithm for establishing mechanisms fordetecting runtime redirection. The mechanisms for detecting runtimeredirection may depend on the operating system environment of thedevice. For example, the mechanisms for detecting runtime redirection inan IOS environment may be different than the mechanisms for detectingruntime redirection in an ANDROID or WINDOWS environment. For example,mechanisms for runtime redirection for the ANDROID environment may beoriented around the Executable and Linkable Format (ELF) instead of animport table and symbol table-oriented design. There may be some commonelements, however, for detecting runtime redirection between thedifferent operating system environments. For example, IOS, ANDROIDand/or WINDOWS environments may use an import table, so mechanisms fordetecting runtime redirection in IOS, ANDROID and/or WINDOWSenvironments may be oriented around the import table. Mechanisms fordetecting runtime redirection in the ANDROID environment may, in someembodiments, be oriented around an import table and symbol table design.The following example of FIG. 6 are directed to establishing mechanismsfor detecting runtime redirection in an operating system environmentthat uses a symbol table and an import table, or otherwise detectsruntime redirection via a process that patches text instructionsegments.

At step 601, a set of system routines that will be replaced may bedetermined. The set of system routines may include system routines thatare called to read or write memory permissions or other input/output(I/O) functions. For example, in some embodiments, the set of systemroutines may include a set of file I/O routines such as ‘open’, ‘read’,‘pread’, ‘pwrite’, and the like for an IOS environment. In somevariations, the set of system routines may include directory handlingfunctions.

At step 603, a table entry from the symbol table for one routine of theset of system routines may be retrieved. Retrieving the table entry mayinclude finding or accessing the symbol table. A symbol table is a datastructure that includes various attributes about a compiled orinterpreted function (as well as other identifiers in source code), suchas a type of the function, a scope of the function, and a memorylocation of the function. Various symbol tables that include tableentries for the one routine of the set of system routines may be in aglobal symbol table (e.g., the global symbol table may include the tableentries for ‘open’, ‘read’, ‘pread’, ‘pwrite’, and the like). Thus, theglobal symbol table may be accessed and iterated through to search forthe table entry of the one routine.

In some embodiments, calls to ‘dlopen’ and ‘dlsym’ may be used toretrieve the table entry for the one routine. For example, passing in anull filename parameter to ‘dlopen’ will return a pointer for the mainprogram that provides access to the global symbol table for the mainprogram. A call to ‘dlsym’ returns an address where the table entry fora particular symbol in a symbol table is located. Thus, to retrieve thetable entry of the one routine, a call to ‘dlsym’ may be made withparameters of the pointer for the main program returned from the‘dlopen’ call and a symbol name of the one routine. The ‘dlsym’ call mayreturn the address for the table entry for the one routine.

At step 605, a memory location or address of the one routine may bedetermined from the table entry for the one routine. In someembodiments, determining the memory location or address of the oneroutine may include access the table entry for the one routine using theaddress for the table entry for the one routine, which was returned fromthe call to ‘dlsym’.

At step 607, the memory location or address of the one routine may beexchanged or set with a memory location or address of a new routine thatincludes code configured to detect an attempt at runtime redirection andto detect an attempt to change in memory permissions. Exchanging orsetting the address of the one routine with the address of a new routinemay include a process similar to that described above in connection withone or more of steps 501, 503 and 505 of FIG. 5. Once exchanged and/orset, the new routine will be executed when a call to the one routine ismade.

The new routine may include additional code that enables the detectionof runtime redirection. The new routine may also include additional codethat enables the determination of whether to allow or deny theredirection. The new routine may further include a call to execute theoriginal implementation of the one routine (e.g., via a self-call, whichcauses the original implementation to be executed due to the call to‘method_exchangeImplementation’; or via a call to the IMP returned from‘method_setImplementation’).

At step 609, it may be determined whether there are additional routinesthat need to be replaced in the set of system routines. For example, ifthe set includes the file I/O routines of ‘open’, ‘close’, ‘pread’ and‘pwrite’, and only the ‘open’ function call has been replaced via steps603-607, the method may proceed back to step 603 to replace the nextfunction in the set of system routines (e.g., ‘close’, ‘pread’ or‘pwrite’). If all of the functions have been replaced, the method mayproceed to step 611. It is noted that while the examples below will bediscussed in terms of the ‘open’, ‘close’, ‘pread’ and ‘pwrite’ systemroutines, other types of system routines could be exchanged or set witha new routine, depending on the API of the operating system environmentand which system routines are selected for inclusion into the set ofsystem routines that will be replaced.

At step 611, detection mechanisms for monitoring calls to one or morevirtual file system operations may be established. In some embodiments,the enterprise mobility management architecture described above mayimplement a virtual file system (VFS) layer. In some operating systemenvironments (e.g., the IOS environment), the VFS layer may beimplemented within a database that stores information for a program orapplication. Some types of databases (e.g., an SQLITE database) may beconfigured to perform pre-processing or post-processing for a specificset of operations issued by the database. Detection mechanisms may beestablished by configuring the database to perform new routines as atleast a part of the pre-processing or post-processing. These newroutines may include additional code that enables the detection ofruntime redirection. These new routines may also include additional codethat enables the determination of whether to allow or deny theredirection.

For example, and as will be discussed in greater detail below, ifdetection mechanisms are established as pre-processing andpost-processing for ‘xRead’ and ‘xWrite’ operations of a VFS interfacefor a SQLITE database, the detection mechanisms can determine whetherthe call to the operation is an attempt to redirect from the currentimplementation of the ‘xRead’ or ‘xWrite’ operation (the currentimplementation can include any pre-processing or post-processing for theoperation), and can then also determine whether to allow or deny thecall. It is noted that while the examples below will be discussed interms of the ‘xRead’ and ‘xWrite’ operations, other types of VFSoperations could be monitored in addition to or as a replacement for the‘xRead’ and ‘xWrite’ operations, depending on database capabilities andwhich VFS operations are selected for monitoring via the detectionmechanisms.

At step 613, memory permissions may be changed to prevent writing toparticular memory segments. For example, after all the system routineshave been exchanged or set via steps 603-607 and call associations havebeen created or saved, memory permissions of memory segments used by adynamic loader may be set to prevent writing (e.g., set to read-only orset to read-execute). As another example, after all the system routineshave been exchanged or set via steps 603-607, an import table has beenprepopulated with various addresses and/or other memory associated withthe import table has been prepopulated with various addresses, thememory locations associated with the various addresses may be set to beread-only. Changing memory permissions may, in some instances, preventattempts to overwrite or otherwise change data stored in particularsegments of memory. Changing memory permissions may, in some instances,increase the effectiveness of the mechanisms for detecting runtimeredirection by requiring an attempt to change memory permissions tooverwrite or otherwise change data stored in particular segments ofmemory.

Additionally, it is noted that step 613 could be performed before allthe system routines have been exchanged or set via steps 603-607, animport table has been prepopulated with various addresses and/or othermemory associated with the import table has been prepopulated withvarious addresses. In such arrangements, steps 603-607 would include theability to catch and handle memory access fault exceptions for memoryaddress ranges associated with the import table.

After establishing the mechanisms for detecting runtime redirection,when various calls to the system routines are made during runtime, theestablished mechanisms may determine whether each call is attempting toperform a redirection or change memory permissions, and may determinewhether to allow or deny the redirection or change. In the followingexample of FIG. 7, the “new routines” of FIG. 6 (see, e.g., step 607 and611 of FIG. 6) will collectively be referred to as “detection routines.”Detection routines may, in some embodiments, be defined as a routinethat includes code configured to detect an attempt to perform a runtimeredirection and detect an attempt to change memory permissions, and/orcode configured to determine whether to allow or deny a detected attemptto perform a runtime redirection or change memory permissions. FIG. 7illustrates an example algorithm for determining whether to allow ordeny a detected redirection or attempt to change memory permissions.

At step 701, during runtime, a call to a system routine that has beenexchanged or set to a detection routine or a call to a VFS operationthat has been established to execute a detection routine aspre-processing may cause a detection routine to be executed. In otherwords, the detection routine is executed in response to a call to acorresponding system routine or VFS operation. For example, if detectionroutines were exchanged or set for the system routines of ‘open’,‘close’, ‘pread’ and ‘pwrite’ (via steps 601-609 of FIG. 6), any call to‘open’, ‘close’, ‘pread’ or ‘pwrite’ may cause a respective detectionroutine to be executed. If detection routines were established toexecute as pre-processing for ‘xRead’ or ‘xWrite’ (via step 613), anycall to ‘xRead’ or ‘xWrite’ may cause a respective detection routine tobe executed. Steps 703-711 of FIG. 7 illustrate features performed by adetection routine during its execution.

At step 703, it may be determined whether the call is an attempt toredirect or change memory permissions. This determination may be made invarious ways and take into account different contextual informationrelated to the call. For example, in making the determination of whetherthe call is an attempt to redirect or change memory permissions, one ora combination of the following may be analyzed or used: the routine oroperation called; the parameters passed to the detection routine via thecall; and/or information of the program stack.

If the determination is based on the routine or operation called, thetype of the routine or operation may be determined and, based on thetype of routine or operation, it may be determined that the call is anattempt to redirect or change memory permissions. For example, if thetype is determined to be a routine or operation that writes to a memorylocation or a virtual file system, such as ‘xWrite’ or ‘pwrite’, thecall may be determined to be an attempt to redirect or change memorypermissions. As another example, if the type is determined to be aroutine or operation that changes a memory permission to a virtual filesystem or other type of memory, it may be determined to be a routine oroperation that writes to a memory location or a virtual file system.

If the determination is based on the parameters passed to the detectionroutine via the call, the parameters may be analyzed and, based on theparameters, it may be determined that the call is an attempt to redirector change memory permissions. For example, if certain parameters arepresent or the parameters have certain values, the call may bedetermined to be an attempt to redirect or change memory permissions.

The determination, in some embodiments, may be based on a combination ofthe type of the routine or operation and the parameters passed to thedetection routine via the call. For example, if the operation or routineis of a particular type (e.g., a routine or operation that writes to amemory location; or a routine or operation that changes memorypermissions) and has a parameter specifying a memory address within aparticular segment of memory (e.g., the memory segment for the originalimplementation of a system routine or the memory segment of a detectionroutine; a memory segment for a virtual file system; or a memory segmentpreviously made read-only via step 613 of FIG. 6), it may be determinedthat the call is an attempt to redirect or change memory permissions.

If the determination is based on information of the program stack, thecontents of the program stack may be analyzed and, based on the contentsof the program stack, it may be determined that the call is an attemptto redirect or change memory permissions. For example, the determinationmay be based on one or a combination of the following, which can bedetermined via the contents of the program stack: which program orroutine made the call; whether there has been a call to ‘dlsym’ or‘dlopen’ within a threshold number of calls; or a location in a programwhere the call was made or where control will be returned uponcompleting the processing associated with the call. In some embodiments,if a third party application (e.g., an application supplied by aprovider different from the manufacturer of the computing device or theemployer) or an unmanaged application from unmanaged partition 312 madethe call, it may be determined that the call is an attempt to redirector change memory permissions. In some embodiments, if there has been acall to ‘dlsym’ or ‘dlopen’ within a threshold of 5 calls, it may bedetermined that the call is an attempt to redirect or change memorypermissions.

If it is determined that the call is an attempt to redirect or changememory permissions, the algorithm may proceed to step 707. If it isdetermined that the call is not an attempt to redirect or change memorypermissions, the algorithm may proceed to optional step 705 or may end.

At optional step 705, if the call to the system routine is determined tonot be an attempt to redirect or change memory permissions, the originalimplementation of the system routine or operation may be called. Forexample, some detection routines, such as the detection routines for thesystem routines of ‘open’, ‘close’, ‘pread’ and ‘pwrite’, will include acall to the original implementation of the system routine (e.g., via aself-call, which causes the original implementation to be executed dueto the call to ‘method_exchangeImplementation’; or via a call to the IMPreturned from ‘method_setImplementation’). Accordingly, a call to theoriginal implementation may be made, which includes the parameterspassed to the detection routine.

In some instances, the call to the original implementation may not beperformed. For example, some detection routines, such as the detectionroutines for the VFS operations of ‘xRead’ and ‘xWrite’, may performsteps 703, 707 and at least portions of steps 709 and 711 as part ofpre-processing of the VFS operation. Accordingly, the VFS operation maybe performed once the pre-processing is complete, so no call needs to bemade by the detection routine.

At step 707, if the call to the system routine is determined to be anattempt to redirect or change memory permissions, it may be determinedwhether to allow or deny the call based on a policy. This determinationmay be made on similar information described above in connection withstep 703. For example, in making the determination of whether to allowor deny the call, one or a combination of the following may be analyzedor used: the routine or operation called; the parameters passed to thedetection routine via the call; and/or information of the program stack.

In some embodiments, the exact information used when performing thedetermination of step 707 may be different from the information usedwhen performing the determination of step 703. For example, if thedetermination of step 703 is based on the routine or operation calledand/or the parameters passed to the detection routine via the call, thedetermination of step 707 may be further based on the information of theprogram stack. For example, it may be determined to allow or deny thecall based on one or a combination of the following, which can bedetermined from the contents of the program stack: which program madethe call; whether there have been any calls to ‘dlsym’ or ‘dlopen’within a threshold number of calls; or a location in a program where thecall was made or where control will be returned upon completing theprocessing associated with the call. As another example, in someinstances, before attempting to change a memory permission to a memorypage to allow writing to the memory page, the address of the memory pagemay be retrieved using a call to ‘dlsym’. Accordingly, it may bedetermined to allow or deny the call based on determining that the callis an attempt to change memory permissions to allow writing to a memorypage and determining that there have been a call to ‘dlsym’ to retrievethe address to the memory page.

Additionally, the information used when performing the determination ofstep 707 in some embodiments may be based on the application that madethe call. For example, some applications may perform internalinitialization that could result in a determination that a call is anattempt to redirect or change memory permissions at step 703. Theinternal initialization may be needed for proper execution of theapplication. Accordingly, the policy may include a listing ofapplications that are allowed to redirect or change memory permissionsand it may be determined to allow the call based on determining that theapplication making the call is on the listing of applications.

If it is determined to allow the call to the system routine or VFSoperation, the algorithm may proceed to step 709. If it is determined todeny the call to the system routine or VFS operation, the algorithm mayproceed to step 711.

At step 709, the call to the system routine may be allowed in accordancewith a policy. For example, a policy may be implemented such that thecall is allowed without modifying the call or the parameters passed tothe detection routine. Accordingly, the original implementation of thesystem routine may be called with the parameters passed to the detectionroutine, or the pre-processing may be completed to allow the VFSoperation to be executed.

Alternatively, a policy may be implemented such that the call is allowedwith modification. For example, the parameters may be modified so that adifferent memory segment is written to, or a different change in memorypermissions is performed. For example, if the call is to change memorypermissions to read-write-execute, the call may be allowed to make achange of read-execute or read-write instead of read-write-execute.

Further, in some instances, features related to allowing the call may beperformed during both pre-processing and post-processing of a VFSoperation. For example, if the call was allowed but with modification,the modification may include pre-processing that changes the data storedin the memory locations of the parameters that were passed to thedetection routine. After the VFS operation is complete, the originalvalues of the parameters may be restored to the memory locations of theparameters.

In some embodiments, the policy may be implemented to determine whetherallow the call with or without modification based on information similarto that discussed above in connection with steps 703 and 707.

At step 711, the call to the system routine may be denied in accordancewith the policy. For example, a policy may be implemented such that thecall is denied and the detection routine throws an exception to theprogram or routine that made the call. Alternatively, a policy may beimplemented such that the call is denied and the detection routinereturns a false indication of success to the program or routine thatmade the call.

Further, in some instances, features related to denying the call may beperformed during both pre-processing and post-processing of a VFSoperation. For example, if the call was denied, the denial may includepre-processing that changes the parameters for the VFS operation to beillegal or otherwise cause no change to be made (e.g., write to anillegal memory location, pass in null values as the parameters, or thelike). After the VFS operation is complete, post-processing may beperformed that restores the original values of the parameters.

In some embodiments, the policy may be implemented to determine whetherto deny the call with an exception or with a false indication of successbased on information similar to that discussed above in connection withsteps 703 and 707.

Additionally, during execution of the detection routine (e.g., steps703-711), a log may be created and/or updated based on the variousdeterminations and other functions performed by the detection routine.For example, the call and the parameters passed to the detection routinemay be logged, the information used when performing the determinationsof steps 703 and 707 may be logged, and information describing how thecall was allowed or denied may be logged.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are described asexample implementations of the following claims.

What is claimed is:
 1. A method comprising: establishing one or moremechanisms that cause, in response to each call to a system routineperformed by a computing device, execution of a routine that includescode configured to detect an attempt to perform a runtime redirection;executing, in response to a first call to the system routine, theroutine that includes the code; based on executing, in response to thefirst call, the routine: determining, based on determining that thefirst call is for writing to a memory location associated with thesystem routine, that the first call is an attempt to redirect from thesystem routine, and based on determining that the first call is anattempt to redirect from the system routine, denying the first call;executing, in response to a second call to the system routine, theroutine that includes the code; and based on executing, in response tothe second call, the routine: allowing the second call.
 2. The method ofclaim 1, wherein establishing the one or more mechanisms includesexchanging or setting an address of the system routine in a globalsymbol table with an address of the routine that includes the code. 3.The method of claim 1, wherein the system routine comprises a fileinput/output (I/O) routine.
 4. The method of claim 1, whereindetermining that the first call is an attempt to redirect from thesystem routine is performed based on information of a program stack. 5.The method of claim 1, wherein denying the first call is performed basedon information of a program stack.
 6. The method of claim 1, wherein thesecond call is associated with one or more parameters, and whereinallowing the second call is performed without modifying the second calland without modifying the one or more parameters.
 7. The method of claim1, wherein the second call is associated with one or more parameters,and wherein allowing the second call is performed with a modification tothe second call or with a modification to the one or more parameters. 8.The method of claim 7, wherein allowing the second call is performedbased on information of a program stack.
 9. The method of claim 1,further comprising: based on denying the first call, throwing anexception or returning a false indication of success.
 10. An apparatuscomprising: one or more processors; and memory storing executableinstructions configured to, when executed by the one or more processors,cause the apparatus to: establish one or more mechanisms that cause, inresponse to each call to a system routine performed by the apparatus oreach call to a virtual file system (VFS) operation performed by theapparatus, execution of a routine that includes code configured todetect an attempt to perform a runtime redirection; execute, in responseto a first call to the system routine or to the VFS operation, theroutine that includes the code; based on executing, in response to thefirst call, the routine: determine, based on determining that the firstcall is for writing to a memory location associated with the systemroutine or to a virtual file system associated with the VFS operation,that the first call is an attempt to redirect from the system routine orfrom the VFS operation; and based on determining that the first call isan attempt to redirect from the system routine or from the VFSoperation, denying the first call; execute, in response to a second callto the system routine or to the VFS operation, the routine that includesthe code; and based on executing, in response to the second call, theroutine: allow the second call.
 11. The apparatus of claim 10, whereincausing the apparatus to establish the one or more mechanisms includescausing the apparatus to exchange or set an address of the systemroutine in a global symbol table with an address of the routine thatincludes the code.
 12. The apparatus of claim 10, wherein causing theapparatus to establish the one or more mechanisms includes causing theapparatus to establish the routine that includes the code to be executedas pre-processing or post-processing for the VFS operation.
 13. A methodcomprising: establishing one or more mechanisms that cause, in responseto each call to a virtual file system (VFS) operation performed by acomputing device, execution of a routine that includes code configuredto detect an attempt to perform a runtime redirection; executing, inresponse to a first call to the VFS operation, the routine that includesthe code; based on executing, in response to the first call, theroutine: determining, based on determining that the first call is forwriting to a virtual file system associated with the VFS operation, thatthe first call is an attempt to redirect from the VFS operation, andbased on determining that the first call is an attempt to redirect fromthe VFS operation, denying the first call; executing, in response to asecond call to the VFS operation, the routine that includes the code;and based on executing, in response to the second call, the routine:allowing the second call.
 14. The method of claim 13, whereinestablishing the one or more mechanisms includes establishing theroutine that includes the code to be executed as pre-processing orpost-processing for the VFS operation.
 15. The method of claim 13,wherein the VFS operation comprises an operation of a VFS interface fora database that stores data for an application.
 16. The method of claim13, wherein determining that the first call is an attempt to redirectfrom the VFS operation is performed based on information of a programstack.
 17. The method of claim 13, wherein denying the first call isperformed based on information of a program stack.
 18. The method ofclaim 13, wherein the second call is associated with one or moreparameters, and wherein allowing the second call is performed withoutmodifying the second call and without modifying the one or moreparameters.
 19. The method of claim 13, wherein the second call isassociated with one or more parameters, and wherein allowing the secondcall is performed with a modification to the second call or with amodification to the one or more parameters.
 20. The method of claim 13,further comprising: based on denying the first call, throwing anexception or returning a false indication of success.